1. Field of the Invention
The invention relates to a surface cleaning apparatus that delivers cleaning fluid to a surface to be cleaned.
2. Description of the Related Art
Extractors are well-known devices for deep cleaning carpets and other fabric surfaces, such as upholstery. Most carpet extractors comprise a fluid delivery system and a fluid recovery system. The fluid delivery system typically includes one or more fluid supply tanks for storing a supply of cleaning fluid, a fluid distributor for applying the cleaning fluid to the surface to be cleaned, and a fluid supply conduit for delivering the cleaning fluid from the fluid supply tank to the fluid distributor. The fluid recovery system usually comprises a recovery tank, a nozzle adjacent the surface to be cleaned and in fluid communication with the recovery tank through a working air conduit, and a source of suction in fluid communication with the working air conduit to draw the cleaning fluid from the surface to be cleaned and through the nozzle and the working air conduit to the recovery tank. An example of an extractor is disclosed in commonly assigned U.S. Pat. No. 6,131,237 to Kasper et al., which is incorporated herein by reference in its entirety.
The U.S. Pat. No. 6,158,081 to Kasen et al. discloses an upright extraction cleaner that has a clean water tank and a detergent tank. A variable solution mixing valve is connected between the outlets from the two tanks and a fluid distributor to create cleaning solution mixtures of variable constituent ratios. A control knob on the outside of the water extraction cleaning machine is connected to the variable solution mixing valve to vary the size of one of the detergent fluid inlet and the clean water inlet so that the ratio of constituent elements can be altered depending upon the cleaning application.